Suppose the amount of tar in cigarettes is described by a normal model with a mean of 3.5 mg

Suppose the amount of tar in cigarettes is described by a normal model with a mean of 3.5 mg and a standard deviation of 0.5 mg. b. In order to advertise as a low tar brand, a manufacturer must prove that their tar content is below the 25th percentile of the tar content distribution. Find the 25th percentile of the distribution of tar amounts.